Sick Chicken

Hi, I was wondering if anyone would have some insight into a problem I am having with my chickens. In the beginning of August one of my silkie hens got sick and died. Whatever was wrong with it happened quickly. It started that it's neck seemed hunched down but it was still walking around fine and eating. Within the next 24 hours the chicken was totally paralyzed from the neck down. We watched the other ones in the flock and they seemed okay. Now last weekend I noticed my rooster straying away from the others, he also seemed clumsy. The rooster would not move he just stood still, so I took him inside with me and shortly after that he died. I have not noticed any symptoms of any kind. The rooster didn't have any problems with his neck or get paralyzed like the hen. If any one could recommend a good chicken vet or a poultry pathology lab to test the next one that dies, it would be greatly appreciated. I live near Dillsburg Pa.
Thanks